Today, the extinct marine reptile is a source of fascination for members of the Dallas Paleontological Society, who have spent the last four years excavating and carefully chipping away at limestone to recover the bones of the vicious animal, which dates back to the Cretaceous period and has been found around the world.

This particular fossil of the 40-to-45-foot-long mosasaur was discovered in a creek in Garland, Texas, in 2008, said Darlene Sumerfelt, a volunteer who has been working on the project.

"Most of the bones were embedded in limestone so they had to be excavated under harsh conditions. We used drill hammers to cut chunks in the limestone and then bring it back to the lab to be prepped," she said. "It's a long process."

The excavation out of the creek took 750 hours, while volunteers from the Dallas Paleontological Society have spent more than 2,000 hours working with slow and steady hands to uncover bones embedded in the limestone, Sumerfelt said.